We investigate the problem of best approximations in the Hardy space of complex functions, defined on the infinite-dimensional unitary matrix group. Applying an abstract Besov-type interpolation scale and the Bernstein-Jackson inequalities, a behavior of such approximations is described. An application to best approximations in symmetric Fock spaces is shown.
"Best Approximations in Hardy Spaces on Infinite-Dimensional Unitary Matrix Groups." Abstr. Appl. Anal. 2014 1 - 8, 2014. https://doi.org/10.1155/2014/631503